A fluid injection flow control device for use in oil wells

ABSTRACT

A fluid injection flow control device for use in oil wells, designed to maintain, the injection rate within a determined layer between two packers, being the puncture zone of an injection well. The device, is axially coupled to a tubing string, consists of a variety of modules formed by an upper coil carrier onto which a primary coil is helically wound which, is connected to the pipe through which the fluid flows, causes a certain load drop in a side-pocket mandrel, which consists of two main parts namely a tubing string that allows for axial tubing continuity and a pocket in which a short or long flow direction vane is installed that determines the outflow towards the unit by way of a transverse opening or its passage to the next module&#39;s corresponding coil through transition tubing.

BACKGROUND OF THE INVENTION

A FLUID INJECTION FLOW CONTROL DEVICE FOR USE IN OIL WELLS, designed to maintain an established range of the injection rate within a given layer between two packers, corresponding to the puncture zone of an injection well, causing a controlled pressure drop of the derived flow to a sector without damaging the molecule of the viscous fluid. The device, which is axially coupled to a tubing string, consists of a variety of modules formed by an upper coil support onto which a primary coil is helically wound, initially connected to the pipe through which the fluid runs, causing a certain load drop in an initial control component known as a side-pocket mandrel. The mandrel consists of two main parts namely the tubing string that allows for axial tubing continuity and the pocket in which a short or long flow direction vane is selectively installed that determines the outflow towards the unit by way of a transverse opening or its passage to the next module's corresponding coil through transition tubing. The implementation of the device for each layer embodies an upper module provided with a pipeline fluid intake port, as many intermediate modules as deemed necessary interconnected via said transition tubing and an end module in which said outlet passage may or may not be blind.

Specifically, the device, that enables Q injection flow rate control, responds to the concept that there are no fluid sources or basins within the control volume and that, pursuant to the Law of Conservation of Matter, the inflow of the bypass tube from the tubing is equal to the outflow, where the p1 pressure of the tube is in direct relation to the unit's p2 pressure.

Thus, as there is a relation between the Q flow that can be injected into the layer, the p1 tubing pressure and the pressure of layer p2, any increase or differential between both pressures would tend to increase or diminish the flow injected.

Accordingly, in order to mitigate flow variations resulting from variances in the p1-p2 pressure equilibrium, certain geometrical parameters can be acted on, that is the tube's inner diameter D (technically complex), or the length L of the tube, which is achieved through the modelling of the coils and their coupling and decoupling to successive modules, with the consequent respective increase or decline in load loss.

In this way discrete changes can be achieved in length L, thereby maintaining the injection flow rate within the range set against changes in the pressure differential.

The device in question is used for controlling the injection flow of viscous fluids, generally polymer chain based, in a specific layer of an oil injection well causing a controlled load loss without affecting its rheological properties.

While attempting to control the flow from surface devices, there is no known means capable of establishing such selective control automatically in each layer and preserving the polymer molecules which provide optimum viscosity.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the primary aim of this patent application is to offer a device capable of maintaining the injection flow rate within a predetermined range in a given layer of an injection well, by producing a controlled pressure drop by virtue of the fact that the different coil length combinations developed as well as their inner diameter enable different flow ratios vs. pressure differentials.

In order to appreciate the advantages thus briefly mentioned and to help understand the constructive and functional characteristics of the flow control device in question for fluid injection in oil wells, a preferred example of the device is described below together with unscaled drawings attached hereto, in addition to a clear statement, that since it is an example, it should not be in any way restrictive, but rather should serve as a merely illustrative view of the basic concept on which it is based,

DESCRIPTION OF THE DRAWINGS AND DESCRIPTION OF THE INVENTION

FIG. 1 shows a device installed in a casing area between an upper packer and a lower packer, which in this particular case consists of three modules, one upper module, an intermediate one, and a lower one; in which the first is connected to the tubing from which it draws the fluid through an intake port connected to the first coil. Helically wound onto the coil carrier section axially fixed to the body of the upper side pocket mandrel whose side pocket, which is specifically the first control component that establishes the continuity of the fluid to the next module or derives it to the casing, receives the fluid from the coil, by means of the transition tube and is connected below by means of another transition tube to the coil that is wound around the coil carrier of the intermediate module. The module 5 is fixed to the intermediate side pocket mandrel provided with its respective side pocket, similar to the previous one, which is connected below by the transition tube with the coil that is wound around the coil carrier of the lower module which is fixed to the lower side pocket mandrel provided with a side pocket with an outlet which may or may not be blind.

FIG. 2 shows how the side pocket of the upper module, has determined the flow of the fluid towards the unit, as indicated by the arrow, by means of a short flow direction vane as seen in FIG. 10.

FIG. 3 shows the side pocket of the upper module, by means of a long flow direction vane, as can be seen in FIG. 9, has determined the continuity of the circuit while the side pocket of the intermediate module, by means of the short flow direction vane, shown in FIG. 10, has determined the fluid flow towards the unit as indicated by the arrow.

FIG. 4 shows the side pocket of the upper module, by means of the long flow direction vane shown in FIG. 9, has determined the continuity of the circuit; the side pocket of the intermediate module, by means of the long flow direction vane shown in FIG. 9, has determined the continuity of the circuit; and the side pocket of the lower module, by means of the short flow direction vane shown in FIG. 13, has determined the flow of the fluid towards the unit as indicated by the arrow.

FIG. 5 illustrates how the upper module is connected to the tubing from which the fluid is drawn by a tapping port connected to the first coil wound helically around the coil carrier section.

FIG. 6 shows a side pocket mandrel, used in the upper or intermediate modules, consisting of a body that is aligned with the tubing and provided with an insulated housing into which the side pocket is welded that establishes the flow control.

FIG. 7 is the cross-section marked VII-VII in FIG. 6, showing the tubing conduit and the side pocket, in which cylindrical housing the corresponding direction vane is placed, providing a passage which integrates it with the circuit.

FIG. 8 is the cross-section marked VIII-VIII in FIG. 6, showing an outlet opening for the flow circulation to the unit. A side pocket provided with a long flow direction vane isolating the passage from the outflow opening towards the unit, determining the absolute continuity of the circuit towards the next module through said passage is illustrated in detail in FIG. 9 (cross section 1X-1X in FIG. 6).

FIG. 10 shows on the other hand, a short flow direction vane has been installed so that, although flow through the passage is enabled, a second flow stream is released into the opening in the direction of the unit.

FIG. 11 shows a side pocket mandrel, used in the lower module, formed by a body aligned with the tubing and provided with an insulated housing into which the side pocket is welded, that establishes flow control.

FIGS. 12 and 13 correspond to the section marked XII-XII in FIG. 11.

FIG. 12 shows the lower side pocket is provided with a long flow direction vane that isolates the blind output passage from the outflow opening towards the unit, determining absolute circuit completion.

FIG. 13 shows however, a short flow direction vane has been installed so that, although the circulation is closed off by the passage since it is blind, an end flow stream is released towards the opening directed towards unit.

The fluids injection flow control device for use in oil wells described and exemplified herein falls within the scope of this application's protection, which is basically established by the text of the following claim sheets. 

1. A fluid injection flow control device for use in oil wells designed to maintain, within an established range, the injection rate of a determined layer between two packers, corresponding to the puncture zone of an injection well, causing a controlled pressure drop of the flow derived to a zone without damaging the molecule of the viscous fluid, wherein the device, which is axially coupled to a tubing string, consists of a variety of successive modules of which an upper module is formed by an upper coil carrier onto which a primary coil is helically wound which is initially connected to piping through which the fluid flows, leads to an initial control element which shall be known as a side-pocket mandrel, which consists of two main parts namely a tubing string that allows for axial tubing continuity and a pocket in which a short or long flow direction vane is selectively installed that determines the outflow towards the unit by way of a transverse opening or its passage to a coil that corresponds to the intermediate module respectively, of similar embodiment, through transition tubing, where a lower module conforms in design to the intermediate module but the pocket outflow passage may or may not be blind.
 2. The fluid injection flow control device for use in oil wells, as claimed in claim 1, wherein the device consists of a variety of intermediate modules.
 3. The fluid injection flow control device for use in oil wells, as claimed in claim 1, wherein the pocket of the upper and intermediate modules is a cylindrical tubular body fixed to the body of the mandrel which defines tubing continuity but is isolated therefrom, the lower end of which is blind and the top end of which permits the insertion or removal of a long or short cylindrical direction vane, said tubular cavity being communicated, in its middle section with a parallel passage which connects its upper and lower ends to the transition tubes of the adjacent modules, whereas, near its lower end, which may or may not be blind, the cylindrical housing has a transverse outlet opening directed at the unit.
 4. The fluid injection flow control device for use in oil wells, as claimed in claim 1, wherein the the pocket of the lower module is a cylindrical tubular body fixed to the body of the mandrel which defines tubing continuity but is isolated therefrom, the lower end of which is blind and the top end of which permits the insertion or removal of a long or short cylindrical direction vane; the tubular cavity being communicated in its middle section with a parallel passage which connects its upper end to the transition tubes approaching from the previous upper module and which lower end is blind, whereas, near its lower end, which may or may not be blind, the cylindrical housing has a transverse outlet opening directed at the unit.
 5. The fluid injection flow control device for use in oil wells, as claimed in claim 1, wherein the long direction vane is a cylindrical stem provided with couplings for its installation at its upper end, which is positioned in the cylindrical pocket housings or, with two hydraulic seal gaskets, one of which is placed prior to the connection of the cylindrical housing with the passages or and the other following said connection and before the transverse outlet openings or, where the communication between said passages and said outlet openings is interrupted.
 6. The fluid injection flow control device for use in oil wells, as claimed in claim 1, wherein the short direction vane is a cylindrical stem provided with couplings for its installation at its upper end, which is positioned in the cylindrical pocket housings or, prior to the connection of the cylindrical housing with the passages or without interrupting the communication between said passages and said outlet opening. 